Apparatus for the continuous spinning of textile fibers

ABSTRACT

Apparatus for the continuous spinning of textile fibers by the open end spinning method, particularly by means of a spinning chamber operating under pressure. The separate spinning units of the apparatus are driven by a common drive from which they are separately disengageable. The spinning chamber of each spinning unit is mounted in a stationary body on the machine frame; the separating and feeding mechanisms of each spinning unit are mounted in a body which is generally movable away from the spinning chamber, whereby to improve the ease with which the spinning units may be attended and maintained.

United States Patent Prochazka et al.

[ 5] Mar. 14, 1972 APPARATUS FOR THE CONTINUOUS SPINNING OF TEXTILEFIBERS Inventors: Miloslav Prochazka; Bedrich Cesenek; Vladimir Mach,all of Nachoda; Karel Kaulich; Zdenka Pacakova, both of Cerveny,Kostelec, all of Czechoslovakia; Ladislav Bradzda, deceased, late ofCerveny Kostelec, Czechoslovakia; Drahuska Brazdova; Dagmar Brazdova,heirs, both of Cerveny Kostelec, (S

Assignee: Said ELITEX, Zavody textilniho Strojirenstvi, generalnireditelstvi, Liberec, Czechoslovakiaby said Prochazka, Cesenek, Mach,Kaulich and Pacakova Filed: Mar. 19, 1970 Appl. No.: 21,157

1 Foreign Application Priority Data Mar. 20, 1969 Czechoslovakia ..PV1984 US. Cl ..57/58.89, 57/58.95

Int. Cl.. ....D0lh l/l2, D0lh 7/00, DOlh 13/26 Field ofSearch..57/58.89, 58.95, 78, 82, 84,

[56] References Cited UNITED STATES PATENTS 2,689,448 9/1954 Winslow etal. ..57/10S 2,807,130 9/1957 Trapido et a1... ....57/l05 UX 3,375,6494/1968 Bures et al ..57/58.91 3,481,129 12/1969 Shepherd et al...57/58.89 3,511,045 5/1970 Bures et a1. ..57/58.95 X

Primary Examiner-Donald E, Watkins Att0rneyArthur O. Klein [5 7]ABSTRACT Apparatus for the continuous spinning of textile fibers by theopen end spinning method, particularly by means of a spinning chamberoperating under pressure. The separate spinning units of the apparatusare driven by a common drive from which they are separatelydisengageable. The spinning chamber of each spinning unit is mounted ina stationary body on the machine frame; the separating and feedingmechanisms of each spinning unit are mounted in a body which isgenerally movable away from the spinning chamber, whereby to improve theease with which the spinning units may be attended and maintained.

12 Claims, 8 Drawing Figures PATENTEDMAR 14 I972 SHEET 3 BF QINVENTOR5'; LADISLAV BRAZDA MILOSLAV PROCHAZKA szolcu ZEsENEK VLADIMIRMACH KAREL. KAULlCH H ZDEpNKA PAcAKovA ATTORNEYS PATENTEUMAR 14 I972SHEET M 0F 4 INVENTORS:

LADISLAV B1112 DA MlLOSLAV PROCHAZKA BE 0 xcH ZesENEK VLADI Mia MACH KREL. KAULJCH ATTORNEYS APPARATUS FOR THE CONTINUOUS SPINNING OF TEXTILEFIBERS The present invention relates to a machine for the continuousspinning of textile fibers by the open end spinning method particularlyby means of a spinning chamber operating under pressure, the separatespinning units in the machine being driven by a common drive from whichthey are separately disengageable.

Several embodiments of the machine for the said spinning method-areknown, such machines differing from each other in the arrangement of thespinning chambers, the separating mechanism, and the feeding mechanismfor the fibrous material. As a result of such differences in arrangementof the elements, the machines differ in function, accessability of theseparate elements, and in their ease of controllability. In the firstknown machines of this type, it was necessary as a matter of coursepartially to disassemble them from time to time, particularly upon thestoppage of the whole machine upon the failure of one of its elements.

As in other textile machines of the same general type, the separateelements and working units of these machines are arranged side by sideon one or both sides of the machine. The oldest known machine of thistype drives the spinning chambers, the separating mechanism and thefeeding mechanism from continuous shafts extending along the wholemachine. In order that such construction shall be feasible as a workingarrangement, it is necessary to choose such a design that the individualelements may be disengaged from the driving means, and that the separatespinning units may be stopped from operation. Without such features theattendance and the operation of the machine as a whole would not befeasible.

In another known machine of this type, the drive for both the spinningchambers and the separating mechanisms is by means of belts which passalong the whole length of the machine. Machines of this type encounterdifficulties, however, when the belt is operated in a horizontal plane.This imposes a considerable radial load upon the bearings of the drivenelements. In such construction, the drive is tangential, in whichminimum contact of the pulley occurs, particularly at the beginning ofthe branch of a belt. The body in which the spinning chamber is mountedtogether with its bearing is swingable; this presents adverse conditionsfor the removal of heat which is generated by the rotary motion of thespinning chamber, and does not provide optimum stability for a longoperating life of the high-speed bearing of the spinning chamber.

The present invention has among its objects the provision of apparatuswhich is at least substantially free of the above pointed outdisadvantages of prior apparatus of this type. In the present apparatusthe separate mechanisms of the spinning units are situated in twobodies, one of which is stationary. Further features of the machineaccording to the present invention are described in the followingspecification and shown in the accompanying drawings, showing preferredbut nonlimiting embodiments of apparatus in accordance with theinvention.

In the drawings:

FIG. I is a fragmentary, somewhat schematic view in front elevation of afirst embodiment of apparatus in accordance with the present invention;

FIG. 2 is a view in vertical transverse section through the apparatus,certain of the parts being shown in elevation, the section being takengenerally along the line II-Il of FIG. 1;

FIG. 3 is a detailed view of a portion of FIG. 2 on a somewhat enlargedscale, the figure particularly showing the drive of the spinningchambers;

FIG. 4 is a fragmentary, somewhat schematic view in side elevation of aportion of the driving mechanism for units at the right-hand side of theapparatus (FIG. 3), the drive for the right-hand two units being showndisengaged;

FIG. 4a is a fragmentary, somewhat schematic view in side elevation of aportion of the driving mechanism for units at the left-hand side of theapparatus (FIG. 3), the drive for the units being shown engaged;

FIG. 5 is a detailed view of the apparatus as it is shown in FIG. 2, theview showing a first embodiment of drive of the separating mechanism ofthe machine;

FIG. 6 is a detailed view of FIG. 2, the view showing the drive of theunit for feeding fibrous material into the spinning units of themachine; and

FIG. 7 is a detailed view similar to FIG. 5 but showing a secondembodiment of drive of the separating mechanism of the machine accordingto the present invention.

It will be understood that the machine of the present invention consistsof a plurality of spinning units of similar construction, such unitsbeing mounted on the machine in side by side relationship on one or bothsides of the machine. Since such spinning units are similar and thedrives therefore as well as other portions thereof are the same, adescription of one such spinning unit and its apertinent parts willsuffice.

In the machine shown there are two longitudinally extending frames 1 onopposite sides of the machine. Other parts of the frame, necessary tothe operation of the machine, are omitted from the drawings in theinterest of simplicity of illustration. Spinning units, which includestationarily mounted spinning chambers 9, and fibrous material feedingmechanism 11, are mounted in outwardly facing position on the respectiveframe members 1. As shown particularly in FIGS. 1 and 2, fibrousmaterial 2 is fed upwardly from spinning cans 2 into the inlet openings11' of the respective spinning units. The yarn 14, produced by therespective spinning units, travels upwardly through the outlet tubes I3between feeding rollers 15, 16 of which the first is in the form of adriven continuous shaft, to be wound upon packages 18 as shown. Suchpackages or bobbins are supported upon swingably mounted levers orframes 19, the bobbins being supported upon and driven by driven drumsin the form of a continuous shaft 17. Traverse mechanism (not shown) isprovided in the vicinity of the drum I7 to relay the yarn across thebobbins in a cross-wound fashion as shown.

A main drive shaft 3, which is positioned horizontally and extendslongitudinally throughout the length of the machine is rotatably mountedin the upper part of the machine frame. A plurality of driving discs 4are mounted upon the shaft 3 at regular intervals, in the embodimentshown there being one such disc 4 for each set of two oppositely mountedspinning units 9, 11. It is to be understood, however, that within thescope of the invention, each driving disc 4 may drive more than twounits. Each driving disc 4 is in operative contact with its respectivedriving belt 5, which is guided over guiding rollers 6 mounted on fixedaxes and over an adjustable tensioning roller 7, as well as over thepulleys 8 of the spinning chambers 9 which are mounted stationarily Inthe bodies 10 on the respective machine frames 1. Assuming that theshaft 3 and the discs 4 mounted thereon rotate clockwise (FIG. 3) thebelt 5 for driving two opposed spinning units travels as follows:Starting at the point S in FIG. 3, the belt 5 travels in contact withthe disc 4 for 180 after which it leaves in a vertical run and istwisted to run about pulley 8 of the right-hand spinning unit or thebelt disengaging pulley 24, to be described. The belt then rises in avertical run offset and free from contact with the disc 4 to theright-hand guide roller 6, being turned 90 in such travel. The belt thentravels approximately about such guide roller 6, downwardly beneath theadjustable tensioning roller 7, up and partially about the lefthandguide roller 6 and then downwardly and about the drive pulley 8 of theleft-hand spinning unit (FIG. 3). As the belt travels downwardly fromthe lefthand guide roller 6 to the driving roller 8 it is turned 90, thebelt being restored to the plane of the periphery of the driving disc 4as it rises from the pulley 8 to engage to disc 4 at the point S.

The bodies 10 together with the: spinning chambers 9 mounted thereinconstitute the stationarily mounted part of the spinning units 12. Theother part of such units, that is, part 11 which is swingably mountedupon pivot pin 12', includes feeding mechanism for the fibrous materialto be processed (FIG. 6), and a separating mechanism (FIG. 5) togetherwith driving trains for such mechanisms, to be described.

As shown in FIGS. 3, 4 and 4a, in the proximaty of each driving pulley 8of a spinning chamber 9 there is provided an arm 22 which is pivotallymounted upon a pivot pin 25 affixed' to frame structure. The arm 22carries a brake shoe 23 and an idle pulley 24, as shown in FIGS. 4 and4a. When the arm 22 is in its inoperative position, toward which isconstantly urged by a coil tension spring 28, the brake shoe 23 andpulley 24 lie spaced from the driving pulley 8 and the beltrespectively. When the ann 22 is swung downwardly into the positionshown in FIG. 4, the brake shoe 23 engages the driving pulley 8 and theguiding pulley 24 then underlies the pulley 8 and removes the belt 5from driving engagement with pulley 8. The arms 22 of the respectivespinning units 12 are under control of mechanism associated with therespective swingable part 11 of the spinning unit, the arms 22 being inthe position shown in FIGS. 4a when the bodies 11 are in their closed,

operative position, the arms 22 being swung into the position shown inFIG. 4 upon the opening of the spinning units 12 by swinging the parts11 outwardly and downwardly.

As shown in FIGS. 3, 4 and 4a each of the arms 22 has a portion whichprojects therefrom outwardly of the pivot pin 25, such projectingportion rotatably mounting rollers 26. Each of the parts 11 of thespinning units 12 has a control member 27 in the form of a segmentconnected thereto, the upper surface of the segment 27 having a camsurface upon which the roller 26 rests. The configuration of such camsurface is such that cause the roller 26 to descend under the action ofthe spring 28 when the parts 11 are in the closed position shown at theleft in FIG. 3, and to cause the rollers 26 to be raised and thus thearms 22 to be rotated into the position shown in FIG. 4 upon theswinging outwardly of part 11 of the spinning unit in the manner shownin FIG. 3. It is to be understood that other linkage mechanisms wherebythe arms 22 are moved from the positions thereof shown in FIG. 4a tothat shown in FIG. 4 upon the opening of the movable part 11 of thespinning unit 12 may be employed. Among such other linkages may be thoseincluding cables, tapes, chains and the like.

The drive for the schematically shown separating mechanisms of therespective spinning units 12, which are mounted in the movable part 11thereof, is derived from continuous longitudinally extending driveshafts 20 which lie beneath the bodies of the spinning units on bothsides of the apparatus. The separating mechanism includes elementsmounted inwardly of the part 11 such elements including a drivenseparating cylinder 31. The separating cylinder 31 is driven by thefollowing elements which are located at one end of the part 11. Adriving disc 30 is fixedly secured to the drive shaft 20 at each of theparts 11 of the spinning units. Disc 11 has frictional drivingengagement with an intermediate roll 33, which in turn fn'ctionallyengages a roller 32 which is affixed to a shaft which extends outwardlythrough the respective end wall of the part 11. The intermediate roller33 is rotatably mounted upon the upper end of the first arm 34 of thebell crank having a second arm 35, the outer end of arm 35 beingpivotally mounted to the part 11 by a pivot pin 36. A coil compressionspring 37 acting between a corner of the part 11 and the arm 35, asshown, constantly urges the intermediate roller 33 into drivingengagement with both the disc 30 and the roller 32, as shown at the leftin FIG. 5. When the body 11 is swung into inoperative position, as shownat the right in FIG. 5, the intermediate roller 33 pulls away from thedisc 30, and so the drive train between the shaft 20 and the separatingcylinder 31 is broken.

The feeding mechanism for the fibrous material, and the driving traintherefor, are shown in FIG. 6. Such feeding mechanism includes a feedingroller 45 mounted within the part 11. The remainder of the parts aredisposed outwardly of the end wall on the part 11. A continuous driveshaft 21 extends along each side of the apparatus as shown. A pinion 40is affixed to a shaft 21 at the location of each of the spinning units;pinion 40 meshes with a larger pinion 41 which is affixed to a shaft 42journalled in the side wall of the part 11. Affixed to gear 41 is asmaller gear 43 which is in mesh with a gear 44, likewise mounted uponthe wall of the part 11. Gear 44 meshes with a smaller gear 46 which isaffixed to the shaft upon which the feeding roller 45 is mounted. Whenthe parts are in their normal, operative relationship they present acontinuous drive train, as shown at the left in FIG. 6, from the shaft26 to the feeding roller 45. When the part 11 is swung outwardly intoits inoperative position, as shown at the right in FIG. 6, the gear 41is disengaged from the gear 40, and so the drive train from the shaft 21to the feeding roll 45 is broken.

The above-described machine, which is shown in FIGS. 1 to 6 inclusive,functions as follows:

The main drive shaft 3 is rotatably driven by means not shown and thusdrives all of the driving discs 4 connected thereto. The discs 4 drivethe respective pulleys of the spinning chambers 9 as above described,thereby imparting a rotary motion to the fibers inside the body 10. Yarn14 being formed by said rotary motion is withdrawn through the outlet 13in the movable part 11 of the spinning unit 12 by the withdrawingrollers l5, 16 which feed said yarn to the winding cylinder 17 by meansof which the yarn is wound upon a bobbin 18. The drive through thedriving pulley 8 of each spinning chamber 9 is stopped by swinging ofthe movable part 11 of the spinning unit 12 outwardly. In its normalworking position, each of the movable parts 11 is held by a latchingmeans such as a magnet 29. Upon the swinging out of the movable part II,the segment 27 moves the arm 22 of the respective spinning unit from theposition shown in FIG. 4a into that shown in FIG. 4, whereby todisengage the driving belt 5 from the respective driving pulley 8. Atthe same time the brake shoe 23 is presented to the driving pulley 8,whereby to bring the spinning part 9 of the unit 12 quickly to a halt.

It will be seen that despite the disengagement of a driving belt 5 fromthe driving pulley 8 of a particular spinning unit, the main shaft 3 andthe driving discs 4 mounted thereon are not stopped. Thus, the spinningunits which derive their drive from such particular belt 5 are notstopped from their normal operation. After the particular part 11 whichhas been moved outwardly is returned into its upright, working position,the pulley 24 is removed from its position between the belt and thedriving pulley 8 so that the driving of the part 9 of the spinning unitis resumed.

As above described, both the separating mechanism and the feedingmechanism for each of the spinning units 12 is mounted in the movablepart 11 thereof. As above described, upon the swinging outwardly of apart 11 of a spinning unit a driving train to both the separatingmechanism and the feeding mechanism therefore are broken. Such drivingtrains are restored upon the swinging of the part from its outwardlytipped position, shown at the right in FIG. 3, to its upright position,shown at the left in FIG. 3 wherein it is held by the latching means 29.

In FIG. 7 there is shown a drive train for the separating mechanismwhich may be substituted for that shown in FIG. 5. The drive train shownin FIG. 7 differs from that of FIG. 5 primarily by the substitution of abelt driving means for a gear train. In the embodiment of FIG. 7 apulley 30' is mounted upon the drive shaft 20 in the vicinity of each ofthe spinning units 12, the pulley 30 driving the separating drum 31 bymeans of a belt 300 which is entrained there over and over a pulley 32'affixed to the outer end of the shaft which mounts the separating drum31. The belt 300 is kept tight by the tensioning roller 301 which ispulled outwardly or forwardly by a coil tension spring 302 one end ofwhich is affixed to the wall of the part 11.

In the embodiment of the driving train for the separating mechanismshown in FIG. 7, interruption of the work of the separating mechanism isalso accomplished by the swinging the part 11 of the spinning unitoutwardly as shown in FIG. 7. In such embodiment, however, despite suchswinging of part 11 the separating drum 31 remains driven by the disc 30acting through the belt 300. It will be seen that the spring 302maintains the tension roll 301 in tight engagement with the belt in bothpositions of the part 11. After returning the movable part into itsworking position, roller 302 resumes its original position and transfersthe rotary motion from disc or pulley 30 on shaft by means of belt 300to the drive pulley 32 of the separating cylinder 31.

In the above described embodiment of the apparatus, one driving disc 4drives the pulleys 8 of two opposed spinning units 12. It is to beunderstood, however, that within the scope of the invention one drivingdisc 4 may drive more than two driving pulleys 8. Thus, with a suitablychosen length of driving belt 5 a various number of spinning chambers 9may be commonly driven. For example, after driving two opposedlydisposed spinning chambers 9, as in the embodiment described above, thebelt may continue along one side of the apparatus in order to drive twoneighboring spinning chambers 9 on such side of the apparatus, crossingover to drive one spinning chamber on the other side of the apparatus,and finally driving two opposedly disposed spinning chambers 9 of theapparatus.

It will be understood, that instead of mounting the parts 11 of thespinning units 12 swingably as above shown and described, they may bemounted slideably with respect to the stationary part 9, 10 of theapparatus.

Although our invention has been illustrated and described with referenceto the preferred embodiments thereof, we wish to have it understood thatit is in no way limited to the details of such embodiments but iscapable of numerous modifications within the scope of the appendedclaims.

What is claimed is:

1. In an apparatus for the continuous spinning of textile fibers by theopen end spinning method, said apparatus having a plurality of spinningunits which are driven by a common drive means and which areindividually disengageable from said drive means, the improved spinningunits which comprise two bodies, one of which is stationary and theother of which is mounted for movement relative thereto betweenoperative and inoperative positions, the outer end of the rotatablydriven element being exposed when the movable body is in its inoperativeposition.

2. Apparatus according to claim 1, wherein the machine has a frame, eachof the spinning units has a spinning chamber, and the spinning chamberis mounted in a stationary body on the machine frame.

3. Apparatus according to claim 1, wherein each of the spinning unitshas a separating mechanism and a feeding mechanism associated therewith,and the separating and feeding mechanisms of the spinning units aremounted in the movable one of the two bodies.

4. Apparatus according to claim 3, wherein the movable body is swingablymounted upon the stationary body.

5. Apparatus according to claim 1, wherein the spinning chambers aredriven by a driving mechanism comprising a main driven shaft extendinglongitudinally of the apparatus, a driving disc on the main driven shaftin the vicinity of each of the spinning units, the spinning chambersbeing provided with driving pulleys, and a plurality of driving beltseach of which is entrained over a respective one of the driving discsand over at least the driving pulleys of two oppositely disposedspinning chambers.

6. Apparatus according to claim 5, comprising two stationarily disposedguiding rollers and an adjustable resiliently biased tensioning rollerpositioned therebetween, the driving belt engaging the guiding andtensioning rollers between its engagement with the driving pulleys ofthe units on the opposite sides of the apparatus.

7. Apparatus according to claim 1, comprising means for selectivelydisengaging the driving belt from the driving pulley of each of thespinning units, said belt-disengaging means comprising abelt-disengaging roller which is interposable between the belt and thedriving pulley for said spinning unit.

8. Apparatus as claimed in claim 7, wherein the belt disengaging rolleris mounted upon an arm, and the arm is selectively moved in oppositedirections by a control element, said control element being connected tothe movable body of the spinning unit, whereby the belt is disengagedfrom the driving pulley of a spinning unit when the movable body of suchunit is moved into inoperative position.

9. Apparatus according to claim 1, comprising driving means for theseparating and feeding mechanisms, said driving means comprising twocontinuous shafts extending along each side of the apparatus above andbelow respectively the stationary body of each of the spinning units.

10. Apparatus according to claim 9, comprising driving trains extendingbetween each of said two longitudinally extending shafts, and a drivingtrain between the respective shafts and the separating mechanism and thefeeding mechanism, said driving train being broken upon the moving ofthe movable body of a spinning unit from its operative to itsinoperative position.

11. Apparatus according to claim 10, wherein both driving trains includeserially meshing gears, one gear in each train being journalcd on anaxis fixed with respect to its driving shaft, another gear, whichnormally meshes with said first gear, being journalcd on the movablebody so as to move out of mesh with the one gear when the movable bodyis moved toward its inoperative position.

12. Apparatus according to claim 9, wherein at least one of the drivingmeans comprises a pulley on the respective shaft, a pulley on therespective shaft, a pulley journalcd on the movable body, a beltentrained over such two pulleys, said belt having an excess length, anda resiliently biased belt-tensioning pulley which pulls the belt into asalient run, whereby the drive through the said driving means continuesdespite the moving of the movable body into its inoperative position.

1. In an apparatus for the continuous spinning of textile fibers by theopen end spinning method, said apparatus having a plurality of spinningunits which are driven by a common drive means and which areindividually disengageable from said drive means, the improved spinningunits which comprise two bodies, one of which is stationary and theother of which is mounted for movement relative thereto betweenoperative and inoperative positions, the outer end of the rotatablydriven element being exposed when the movable body is in its inoperativeposition.
 2. Apparatus according to claim 1, wherein the machine has aframe, each of the spinning units has a spinning chamber, and thespinning chamber is mounted in a stationary body on the machine frame.3. Apparatus according to claim 1, wherein each of the spinning unitshas a separating mechanism and a feeding mechanism associated therewith,and the separating and feeding mechanisms of the spinning units aremounted in the movable one of the two bodies.
 4. Apparatus according toclaim 3, wherein the movable body is swingably mounted upon thestationary body.
 5. Apparatus according to claim 1, wherein the spinningchambers are driven by a driving mechanism comprising a main drivenshaft extending longitudinally of the apparatus, a driving disc on themain driven shaft in the vicinity of each of the spinning units, thespinning chambers being provided with driving pulleys, and a pluralityof driving belts each of which is entrained over a respective one of thedriving discs and over at least the driving pulleys of two oppositelydisposed spinning chambers.
 6. Apparatus according to claim 5,comprising two stationarily disposed guiding rollers and an adjustableresiliently biased tensioning roller positioned therebetween, thedriving belt engaging the guiding and tensioning rollers between itsengagement with the driving pulleys of the units on the opposite sidesof the apparatus.
 7. Apparatus according to claim 1, comprising meansfor selectively disengaging the driving belt from the driving pulley ofeach of the spinning units, said belt-disengaging means comprising abelt-disengaging roller which is interposable between the belt and thedriving pulley for said spinning unit.
 8. Apparatus as claimed in claim7, wherein the belt disengaging roller is mounted upon an arm, and thearm is selectively moved in opposite directions by a control element,said control element being connected to the movable body of the spinningunit, whereby the belt is disengaged from the driving pulley of aspinning unit when the movable body of such unit is moved intoinoperative position.
 9. Apparatus according to claim 1, comprisingdriving means for the separating and feeding mechanisms, said drivingmeans comprising two continuous shafts extending along each side of theapparatus above and below respectively the stationary body of each ofthe spinning units.
 10. Apparatus according to claim 9, comprisingdriving trains extending between each of said two longitudinallyextending shafts, and a driving train between the respective shafts andthe separating mechanism and the feeding mechanism, said driving trainbeing broken upon the moving of the movable body of a spinning unit fromits operative to its inoperative position.
 11. Apparatus according toclaim 10, wheRein both driving trains include serially meshing gears,one gear in each train being journaled on an axis fixed with respect toits driving shaft, another gear, which normally meshes with said firstgear, being journaled on the movable body so as to move out of mesh withthe one gear when the movable body is moved toward its inoperativeposition.
 12. Apparatus according to claim 9, wherein at least one ofthe driving means comprises a pulley on the respective shaft, a pulleyon the respective shaft, a pulley journaled on the movable body, a beltentrained over such two pulleys, said belt having an excess length, anda resiliently biased belt-tensioning pulley which pulls the belt into asalient run, whereby the drive through the said driving means continuesdespite the moving of the movable body into its inoperative position.